The present invention relates to a high viscosity xanthan gum formed by heat treatment and compositions comprising such xanthan gum.
Xanthan gum is a polysaccharide gum derived from the bacterium Xanthomonas and is well known in the art. It is composed of a main chain comprising β-(1,4) D-glucose units. Trisaccharide side chains on alternating anhydroglucose units are composed of a glucuronic acid residue between two mannose units. At most of the terminal mannose units is a pyruvate moiety and the non-terminal mannose carries an acetyl group. It has pseudoplastic or shear-thinning behavior characterized by a decrease in apparent viscosity in response to an increase in shear rate.
Xanthan gum is typically used in many industrial applications as a rheology modifier; thickening, viscosifying and gelling when combined with other polymers. It has also been used to impart stability to emulsions and prevent the settling out of solids. Its limited ability to disperse in either hot or cold water allows xanthan gum to be formulated into a broad variety of applications including pharmaceuticals, household products, foods, and personal care products.
Xanthan gum is widely used in cosmetics and personal care industry as a rheology control agent for aqueous systems. However, currently available xanthan gums need to be improved to enhance its properties, broaden its applications, and provide functionality at a lower cost.
Xanthan gum with an apparent average molecular weight of greater than 16,000,000 has been used to stabilize and improve the feel of emulsified cosmetics such as toilet water, creams and cleansing gels (JP Application No. 10-140503).
Xanthan gum which has been heat-treated is also known in the art. For example, EP 321 216 enhances the viscosity profile of xanthan gum by thermally treating it in the dry state (15% moisture or less). Heat treatment of xanthan gum is also known in JP Application No. 8-193055 which heat treats xanthan gum in the powdered form.
Surprisingly, it has now been discovered that certain heat treated xanthan gums have superior solution viscosity and thickening efficiency while maintaining the improved ease of use and the short, non-stringy gel texture of heat treated xanthan gums. Such high solution viscosity xanthan gums are suitable in a variety of applications, including cosmetic and personal care compositions.